Hydrolysis-optimized lipid emulsions and use thereof

ABSTRACT

The present invention pertains to hydrolysis-optimized isotonic lipid emulsions comprising medium-chain triglycerides (MCT), vegetable oils and fish oil, as well as their use for parenteral nutritition.

This application is a Rule 371 of PCT/EP96/05184, filed Nov. 23, 1996.

The present invention pertains to hydrolysis-optimized isotonic lipidemulsions (fat emulsions) for parenteral administration, in particularfor parenteral nutrition, and their use in situations of exaggeratedinflammatory response (e.g. post-surgery, post-trauma, sepsis,inflammatory or wasting diseases) or of increased risk of vascularthrombosis and severe cardiac arrytlmia where it is important to avoidinflicting an exogeneous triglyceride accumulation while making freefatty acids available to different tissues of the body as rapidly aspossible.

Lipid emulsions for parenteral nutrition serve to supply the body withfats in an intravenously acceptable dosage form when normal (oral)nutrition is impossible, compromised or medically contraindicated orwhen it is necessary to promptly modify the fatty acid pattern of thecells. The lipid emulsions currently available are prepared fromvegetable oils (e.g. safflower or soybean oils); in some cases they alsocontain medium-chain triglycerides (MCT) and/or oils of marine origin(fish oils).

Long-chain triglycerides of vegetable or marine origin serve as anenergy source and, when containing polyunsaturated fatty acids, assuppliers of essential fatty acids. The classification of suchpolyunsaturated fatty acids into omega-6 or omega-3 series types isbased on chemical structural features, more precisely, on the distanceof the first unsaturated bond from the methyl end (omega end) of thefatty acid molecule.

The vegetable oils, e.g. of soybean and safflower, are characterized bya high content of polyunsaturated fatty acids of the omega-6 series(predominantly linoleic acid, 18:2 n-6) whereas their content of omega-3fatty acids (almost exclusively in the form of α-linolenic acid, 18:3n-3) is low.

Fish oils obtained from cold-water fish are characterized by a highcontent of polyunsaturated fatty acids of the omega-3 series(predominantly eicosapentaenoic acid, EPA, 20:5 n-3, and docosahexenoicacid, DHA, 22:6 n-3) whereas their content of omega-6 fatty acids islow.

The medium-chain triglycerides administered with the lipid emulsionsserve mainly as a source of energy. Medium-chain triglycerides do notcontain any unsaturated fatty acids and hence contain neither omega-6nor omega-3 essential fatty acids.

Numerous clinical observations underline the principal suitability oflipid emulsions for parenteral nutrition and for substituting essentialfatty acids in severe diseases and the metabolic conditions involved.

The human body is itself incapable of producing the vital,polyunsaturated long-chain fatty acids of the omega-6 or omega-3 series;i.e. they have to be administered orally, enterally or parenterally. Thebody is only able to synthesize longer-chain unsaturated fatty acidsfrom shorter-chain ones; formation of omega-6 fatty acids fromprecursors of the omega-3 series or vice versa is impossible, however.

Correspondingly, there is a need for lipid emulsions for parenteraladministration which contain medium-chain triglycerides as well astriglycerides of omega-6 and omega-3 fatty acids as lipid components.

EP-A-0 311 091 describes isotonic lipid emulsions for parenteralnutrition comprising, in addition to conventional additives andauxiliary agents, omega-3 fatty acids, omega-3 fatty acids in the formof their esters or as components of fish oils, medium-chaintriglycerides, as well as optionally at least one vegetable oilproviding omega-6 fatty acids in a proportion of up to 30%, based on thelipid content of the emulsion.

DE-OS-37 21 137 describes lipid emulsions for parenteral nutritioncomprising eicosapentaenoic acid triglyceride and/or docosahexaenoicacid triglyceride, or fish oils containing such triglycerides, as wellas vegetable oils containing omega-6 fatty acids, and medium-chaintriglycerides.

DE-OS-34 09 793 describes a lipid emulsion for transfusion comprising afatty acid containing from 20 to 22 carbon atoms, esters thereof, or amixture of 2 or more of such fatty acids or esters, as well as avegetable oil, an emulsifier, and water. Said fatty acids are fattyacids from esters of marine origin (fish oils), in particular omega-3fatty acids. Said vegetable oils are purified soybean and/or saffloweroils.

In order that the exogeneous free fatty acids are made available to thebody, they must either be released hydrolytically from the infusedtriglycerides by means of the enzyme lipoprotein lipase (LPL) or hetaken up together with emulsion particles or their remnants directlyinto the cells. This initial step of lipidhydrolysis has long beenconsidered the rate-determining step of lipid metabolism. Thislimitation arises from the relatively limited activity of lipoproteinlipase in cleaving triglycerides Thus, the maximum metabolizing rate forvegetable oil emulsions is about 3.8 g of lipid/kg body weight per day(Hallberg et al., Acta Physiol. Scand., Vol. 65, Suppl. 254 (1965), p.2-23).

During triglyceride infusion, it is desirable, to achieve triglycerideserum concentrations which are as low as possible, e.g. corresponding toa low load of the reticulo-endothelial system (RES) by exogenous lipid.

Typically, post-operative and post-traumatic conditions as well assevere septic episodes are characterized by a substantial stimulation ofthe immune system. The immune response involves the release of cytokines(e.g. tumor necrosis factor and inter-leukins) which, at high levels,may cause severe tissue damage. In addition, high cytokineconcentrations also impair hydrolysis of circulating triglycerides byLPL.

In such clinical conditions, it is of particular importance to useexogeneous triglycerides which are rapidly hydrolyzed and eliminated andwhich contain fatty acids (e.g. omega-3 fatty acids) capable of reducingcytokine production as well as cytokine toxicity on tissues.

Fatty acids as an energy substrate (for oxidative purposes) and forincorporation in membranes (for structural purposes) and as precursorsof eicosanoids should also be made available to the body as quickly aspossible.

Triglycerides typical of fish oils are hydrolyzed much more slowly thantriglycerides from vegetable oils (e.g. soybean oil) which arethemselves hydrolyzed more slowly than medium-chain triglycerides.Addition of a fish oil emulsion to a long-chain triglyceride emulsioncan even inhibit hydrolysis of long-chain triglycerides (e.g. fromsoybean oil) by LPL.

Therefore, it is an object of the invention to provide a lipid emulsionfor parenteral nutrition capable of being parenterally administeredwhich has been optimized with respect to hydrolysis and elimination,which means that the triglycerides supplied with said lipid emulsion arehydrolyzed in the body extra- or intracellularly, i.e. cleaved to freefatty acids and glycerol, as quickly as possible without concomitantexcessive increase of the serum level of free fatty acids. This impliesthat more lipids can be administered to the body parenterally within thesame period of time without an increase of lipid concentration orconcentration of hydrolysis products.

This object has been achieved by a hydrolysis-optimized isotonic aqueouslipid emulsion for parenteral administration comprising, based on thetotal lipid content of the lipid emulsion:

from 30% to 60% by weight of medium-chain triglycerides;

from 35% to 65% by weight of at least one vegetable oil comprisingtriglycerides which supply omega-6 fatty acids;

from 5% to 20% by weight of at least one fish oil comprisingtriglycerides which supply omega-3 fatty acids; and

conventional auxiliary agents and/or additives.

Surprisingly, it has been found that the object of the invention may beachieved by combining in the same emulsion particle medium-chaintriglycerides, vegetable oils rich in omega-6 fatty acids, and fish oilscontaining omega-3 fatty acids in the quantitative proportion mentionedabove. In particular, it has been found that the MCT/vegetable oil/fishoil mixtures of the invention are more quickly hydrolyzed than knownMCT/vegetable oil mixtures and MCT/vegetable oil/fish oil mixtures ofthe prior art. Thus, triglyceride load of the body by exogeneoustriglycerides is avoided. Medium-chain fatty acids and long-chainessential fatty acids become quickly available to the body. Thisinvolves no significant increase of the serum concentration of freefatty acids despite the fact that more lipids are supplied to the bodyper unit of time. Further, rapid incorporation of omega-3 fatty acids inplatelet and leucocyte membrane phospholipids can be observed.

The lipid emulsions according to the invention include emulsifiedmixtures of oils (lipids) rather than mixtures of the emulsions.

According to the invention, those medium-chain triglycerides are usedwhich have chain lengths of fatty acid ranging from C₆ to C₁₄ and whichare comprised of at least 90% by weight of triglycerides of caprylicacid (C₈) and capric acid (C₁₀). The fraction of medium-chaintriglycerides, based on the total lipid content of the lipid emulsion,is preferably from 45% to 55%, more preferably from 48% to 52%, byweight.

The lipid emulsions according to the invention further contain at leastone vegetable oil containing triglycerides made predominantly of omega-6fatty acids.

Preferred vegetable oils are safflower oil and/or soybean oil, thecontent of such vegetable oils in the lipid emulsion preferably beingfrom 35% to 45%, more preferably from 38% to 42%, by weight, based onthe lipid content of the lipid emulsion. The vegetable oils containtriglycerides of fatty acids having chain lengths of C₁₆ to C₂₀ andpredominantly contain triglycerides of omega-6 fatty acids.

Fish oils are known to contain eicosapentaenoic acid (EPA, 20:5 n-3) anddocosahexaenoic acid (DHA, 22:6 n-3) incorporated in triglycerideswhich, being so-called highly unsaturated omega-3 fatty acids, areessential building blocks which have to be supplied to the body andwhich are biologically important, for example, as precursors ofeicosanoids and as structural elements of membrane lipids. These acidsare further attributed antithrombotic and lipid-lowering actions. Sincetheir isolation from natural products and their chemical synthesis isexpensive, fish oils, being relatively inexpensive, are the suppliers ofchoice for such essential fatty acids. As used in the invention, theterm "fish oils" is intended to comprise natural fish oils, processedfish oils, or highly purified fish oil concentrates. According to theinvention, processed fish oils may also be used, such as described e.g.in EP-A-0 298 293 which is incorporated herein by reference.

Suitable exemplary fish oils are oils which are obtained from cold waterfish on a technically significant scale or oils which are syntheticallyobtainable by esterification of omega-3-fatty acids (obtained from fishoil of cold water fish, preferably salmon, sardine, mackerel, herring,anchovy, smelt and swordfish, by hydrolysis of the triglycerides andsubsequent purification and concentration of the resultant omega-3-fattyacids) with glycerol. Fish oils generally contain triglycerides of fattyacids having chain lengths of from 12 to 22 carbon atoms. Particularlypreferred are highly purified fish oil concentrates which are obtained,for instance, from sardine, salmon, herring and/or mackerel oils. Theyhave an eicosapentaenoic acid content of from 20 to 40%, preferably atleast 25%, based on the fatty acid methyl esters of the fish oilconcentrate as determined by gas chromatography (percent by area).Furthermore, they have a docosahexaenoic acid content of from 10 to 20%,preferably at least 12%, based on the fatty acid methyl esters of thefish oil concentrate as determined by gas chromatography (percent byarea). In case of the fish oils which are synthetically obtainable bythe re-esterification of the omega-3-fatty acids the total concentrationof eicosapentaenoic+docosahexaenoic acid can be at least 45% on basis ofthe triglycerides.

It is particularly preferred to use a fish oil rich in EPA wheninflammatory processes are to be influenced. Fish oil rich in DHA isparticularly preferred in pediatric patients in the case of omega-3fatty acid deficiency to influence growth and maturation of the centralnervous system.

Preferably, the content of fish oil, based on the total lipid content ofthe lipid emulsion, is from 10% to 20%, more preferably from 10% to 14%,by weight.

The total lipid content of the lipid emulsion is from 5% to 30%,preferably from 10% to 25%, by weight, based on the aqueous lipidemulsion.

In addition to distilled water, the isotonic lipid emulsion contains theusual auxiliary agents and/or additives, such as emulsifiers,emulsifying aids (co-emulsifiers), stabilizers. antioxidants, andisotonizing additives.

As emulsifiers, physiologically acceptable emulsifiers are used, such asphospholipids of animal or vegetable origin. Particularly preferred arepurified lecithins, especially soybean lecithin, egg lecithin, orfractions thereof, or the corresponding phosphatides. The emulsifiercontent is from 0.6% to 1.5%, preferably 1.2%, by weight, based on thetotal emulsion.

Further, alkali metal salts of long-chain, C₁₆ to C₂₀, fatty acids maybe used as emulsifying aids (co-emulsifiers). Especially preferred aretheir sodium salts. The co-emulsifiers are employed in concentrations offrom 0.005% to 0.1%, preferably 0.02% to 0.04%, by weight, based on thetotal emulsion. Further, cholesterol or a cholesterol ester alone or incombination with other co-emulsifiers may be employed in a concentrationof from 0.005% to 0.1%, preferably from 0.02% to 0.04%, by weight.

The lipid emulsion according to the invention may contain vitamin E, inparticular α-tocopherol, and/or ascorbyl palmitate as antioxidants andthus for protection from peroxide formation in amounts of from 10 to1000 mg, preferably 25 to 200 mg, based on 100 g of lipid.

For stabilization and isotonization, the emulsion according to theinvention may contain from 2% to 5% by weight of a stabilizing orisotonizing additive, for example, a polyhydric alcohol. In thisconnection, glycerol, sorbitol, xylitol or glucose are preferred,glycerol being particularly preferred.

The lipid emulsions according to the invention are invariablyoil-in-water (o/w) emulsions in which the outer, continuous phaseconsists of distilled water purified for parenteral purposes Such o/wemulsion is obtained by mixing MCT, vegetable oil and fish oil andsubsequent emulsification. After sterilization, the lipid emulsion has apH of from 6.0 to 9.0, preferably from 6.5 to 8.5.

The isotonic lipid emulsions according to the invention can be preparedby known procedures with inertization. The usual approach is first tomix the lipids, emulsifier and other auxiliary agents and additives andthen to fill up with water with dispersing. The water may optionallycontain additional water-soluble components (e.g. glycerol). Theemulsion thus obtained still contains lipid particles having a diameterof about 10 μm. The average droplet size of the emulsion must thenfurther be reduced by additional homogenization, e.g. using ahigh-pressure homogenizer. For parenteral application, medium lipiddroplet sizes of less than 1.0 μm, in particular less than 0.5 μm, arepreferred.

The lipid emulsions according to the invention are used for parenteraladministration, in particular parenteral nutrition, of patients withexaggerated inflammatory responses or increased risk of vascularthrombosis or severe cardiac arrythmia. In particular, the lipidemulsions according to the invention can be used with patients inpost-operative and post-traumatic conditions or inflammatory diseases;further, e.g., in severe or persistent post-aggression metabolismfollowing operations, such as abdominal operations or organtransplantations, and multiple trauma, inflammatory diseases, burns,infections, impending or manifest sepsis, impaired respiratory function,conditions of excessive production of cytokines, wasting diseases, andincreased risk of severe cardiac arrythmia (e.g. ventricularfibrillation) or vascular thrombosis. The lipid emulsion according tothe invention can also be used for parenteral nutrition following shockconditions for improving microperfusion and metabolic performance oforgans poorly supplied with blood in terms of metabolic reanimation.

The invention will be illustrated by the following examples.

PREPARATIVE EXAMPLES

Table 1 shows the fatty acid composition (approx. %) of various oilsused in the lipid emulsions of the following examples:

                  TABLE 1                                                         ______________________________________                                                  MCT      Soybean    Safflower                                                                              Fish                                     Fatty acid oil.sup.1) oil.sup.2) oil.sup.3) oil.sup.4)                      ______________________________________                                        6:0       <2       --         --       --                                       8:0 64 -- -- --                                                               10:0 34 -- -- --                                                              12:0 <3 -- -- <1                                                              14:0 <1 -- -- 5                                                               16:0 -- 11 7 10                                                               16:1 -- -- -- 7                                                               16:2 -- -- -- 1                                                               16:3 -- -- -- 1                                                               16:4 -- -- -- 3                                                               18:0 -- 4 3 1                                                                 18:1 -- 22 14 10                                                              18:2 n-6 -- 55 75 2                                                           18:3 n-3 -- 8 <1 1                                                            18:4 n-3 -- -- -- 4                                                           20:0 -- <1 <1 --                                                              20:1 -- <1 <1 2                                                               20:4 n-6 -- -- -- 2                                                           20:5 n-3 -- -- -- 28                                                          22:1 -- -- -- 1                                                               22:4 -- -- -- <1                                                              22:5 -- -- -- 3                                                               22:6 n-3 -- -- -- 13                                                          Σ n-6 -- 55 75 4                                                        Σ n-3 -- 8 <1 46                                                        n-6:n-3 -- 7:1 ≧75:1 1:12                                            ______________________________________                                         .sup.1) medium chain triglycerides, e.g. Captex 355, commercial product o     Karlshamns.                                                                   .sup.2) soybean oil, e.g. Sojaol, commercial product of Croda.                .sup.3) safflower oil, e.g. Saflorol, commercial product of Gustav Heess.     .sup.4) highly purified fish oil, e.g. Sanomega S2BGA, commercial product     of Nippon Oil and Fats.                                                  

Mixture I containing MCT, vegetable oil, fish oil, emulsifier(fractionated phospholipids from chicken egg yolk) is dispersed by meansof Ultra-Turrax and filled up with aqueous component II with stirring.The pH value is adjusted to pH 8.0 to 9.0 using an aqueous sodiumhydroxide solution and/or sodium oleate. Subsequent homogenization isperformed in a high-pressure homogenizer at 400 kg/cm². After dispensingin glass bottles of appropriate grade, heat sterilization is performedby known methods.

                                      TABLE 2                                     __________________________________________________________________________                  1 (comparative        5 (comparative                              Preparative Example example 1*) 2 3 4 example 2**)                          __________________________________________________________________________    I.                                                                              medium-chain triglycerides                                                                1000 g 500 g                                                                              1000 g                                                                             1000 g                                                                             1000 g                                       from partial synthesis                                                        purified safflower oil -- -- 800 g --                                         purified soybean oil 1000 g 400 g -- 800 g 600 g                              highly purified fish oil -- 100 g 200 g 200 g 400 g                           cholesterol acetate -- -- 2 g --                                              purified phospholipids 120 g 90 g 120 g 120 g 120 g                           from: egg egg egg egg egg                                                     α-tocopherol 2000 mg 1000 mg 2000 mg 2000 mg 2000 mg                    ascorbyl palmitate 1500 mg -- 1000 mg 1500 mg 1500 mg                         sodium oleate 3,0 g 2,5 g -- 3,0 g 3,0 g                                     II. glycerol 250 g 250 g 250 g 250 g 250 g                                     NaOH -- -- to pH -- --                                                           8.0-9.0                                                                    water for injections ad 10 I ad 10 I ad 10 I ad 10 I ad 10 I               __________________________________________________________________________     *MCT/vegetable oil (50:50)                                                    **MCT/vegetable oil/fish oil (50:30:20) according to EPA-O 311 091       

A sterile and pyrogen-free, stable emulsion resulted containing lipiddroplets having an average size of less than 0.5 μm with a shelf-life atroom temperature of at least 18 months.

EXAMPLE 1

(in vivo)

1. Determination of Triglyceride Hydrolysis

Eight male subjects (age (av. ±st.d.) 23±3 years) were infused with alipid emulsion of MCT/vegetable oil (50:50) over 5 h each on 4successive days (treatment A, table 3; preparative example 1 in table2). After an interval of four weeks, a lipid emulsion of MCT/vegetableoil/fish oil (50:40:10) was infused under the same conditions (treatmentB, table 4; preparative example 4 in table 2). After another interval ofat least eight weeks, a lipid emulsion of MCT/vegetable oil/fish oil(50:30:20) was infused under the same conditions (treatment C, table 5;preparative example 5 in table 2). Triglyceride hydrolysis in the serum(measured as the average infusion rate in mg of lipids/kg body weight/hunder triglyceride clamp conditions at a serum concentration of 3.0mmol/l from 3rd to 5th hours of infusion, 9 measurements per subject andper day; analysis of variance) was determined as follows:

                  TABLE 3                                                         ______________________________________                                        Treatment A (Comparative Example 1)                                             Average infusion rate (3rd to 5th hour) with an MCT/vegetable                 oil (50:50) emulsion [mg of lipids/kg body weight/h]                            Subject    Day 1       Day 2  Day 3                                       ______________________________________                                        1.         171         155      180                                             2.  98 103 101                                                                3. 142 161 122                                                                4. 180 175 166                                                                5. 182 223 243                                                                6. 203 259 269                                                                7. 129 129 143                                                                8. 188 221 170                                                                average ± st.d. 162 ± 35 178 ± 53 174 ± 57                      ______________________________________                                    

                  TABLE 4                                                         ______________________________________                                        Treatment B (according to the invention)                                        Average infusion rate (3rd to 5th hour) with an MCT/vegetable                 oil/fish oil (50:40:10) emulsion [mg of lipids/kg bodyweight/h]                 Subject    Day 1       Day 2  Day 3                                       ______________________________________                                        1.         224         236      203                                             2. 201 134 163                                                                3. 186 199 182                                                                4. 190 201 179                                                                5. 255 278 273                                                                6. 259 272 271                                                                7. 147 154 142                                                                8. 176 182 181                                                                average ± st.d. 205 ± 39 207 ± 52 199 ± 48                      ______________________________________                                    

                  TABLE 5                                                         ______________________________________                                        Treatment C (Comparative Example 2)                                             Average infusion rate (3rd to 5th hour) with an MCT/vegetable                 oil/fish oil (50:30:20) emulsion [mg of lipids/kg body weight/h]                Subject    Day 1       Day 2  Day 3                                       ______________________________________                                        1.         202         192      186                                             2. 133 122 120                                                                3. 147 148 174                                                                4. 228 211 204                                                                5. 233 241 231                                                                6. 168 250 259                                                                7. 147 189 161                                                                8. 174 177 188                                                                average ± st.d. 179 ± 36 191 ± 41 190 ± 40                      ______________________________________                                    

Triglyceride hydrolysis under treatment B according to the invention wassignificantly higher than that under treatments A (p<0.0001) and C(p<0.05) for all days of treatment. Thus, the average infusion rate overthree days was 4.9 g of triglycerides/kg body weight/day for the lipidemulsion of MCT/vegetable oil/fish oil (50:40:10), and 4.1 and 4.5 g oftriglycerides/kg body weight/day, respectively, for the lipid emulsionsof MCT/vegetable oil (50:50) and MCT/vegetable oil/fish oil (50:30:20).The lipid emulsions composed according to preparative examples 2 and 3give similar results. The result of a more rapid hydrolyzation of thelipid emulsions according to the invention to give free fatty acids ascompared to the concentional lipid emulsions of the prior art can alsobe confirmed by in vitro studies (cf. example 2).

2. Determination of the Level of Free Fatty Acids in the Serum

The level of free fatty acids in the serum of the subjects wasdetermined on the days of treatment before (0 h) and immediatelyfollowing (5 h) administration of the lipid emulsion. A suitable testfor this purpose is, for instance, NEFAC test (an in vitro enzymaticcolorimetric method) of Wako Chemicals GmbH, Germany.

It has been found that upon administration of the lipid emulsion ofMCT/vegetable oil/fish oil (50:40:10) according to the invention theserum concentrations of free fatty acids are not increased to markedlyhigher values as compared to administration of a commercial lipidemulsion of MCT/vegetable oil (50:50) and another lipid emulsion ofMCT/vegetable oil/fish oil (50:30:20) although more lipids have beensupplied to the body per unit of time. The experimental results aregiven hereinafter in tables 6 and 7:

                  TABLE 7                                                         ______________________________________                                        Treatment B (according to the invention)                                        Free Fatty Acids in the Serum [μmol/l],                                    MCT/vegetable oil/fish oil (50:40:10)                                         Subject    after   Day 1    Day 2   Day 3                                   ______________________________________                                        1.       0 h     18         0       28                                           5 h 1321 1421 1102                                                           2. 0 h 298 254 431                                                             5 h 1252 1101 1038                                                           3. 0 h 7 14 26                                                                 5 h 1363 1286 1239                                                           4. 0 h 25 8 7                                                                  5 h 1179 1197 1095                                                           5. 0 h 0 11 30                                                                 5 h 1165 1502 1381                                                           6. 0 h 4 0 19                                                                  5 h 1556 1295 1417                                                           7. 0 h 70 88 75                                                                5 h 1053 983 963                                                             8. 0 h 0 12 0                                                                  5 h 1421 941 1012                                                            Average ± st.d. 0 h 53 ± 95 48 ± 82  77 ± 135                      5 h 1289 ± 150  1216 ± 187  1156 ± 160                            ______________________________________                                    

                  TABLE 6                                                         ______________________________________                                        Treatment A (Comparative Example 1)                                             Free Fatty Acids in the Serum [μgmol/l], MCT/vegetable oil (50:50)         Subject    after   Day 1    Day 2   Day 3                                   ______________________________________                                        1.       0 h     0          22      39                                           5 h 921 921 1068                                                             2. 0 h 399 202 143                                                             5 h 996 742 762                                                              3. 0 h 57 48 48                                                                5 h 1554 144 1408                                                            4. 0 h 52 71 44                                                                5 h 1212 1173 979                                                            5. 0 h 20 23 10                                                                5 h 903 1272 1405                                                            6. 0 h 28 41 82                                                                5 h 1082 1271 1449                                                           7. 0 h 97 90 122                                                               5 h 1068 949 1169                                                            8. 0 h 27 47 34                                                                5 h 1219 1236 1140                                                           Average ± st.d. 0 h  85 ± 122  68 ± 55  65 ± 43                    5 h 1119 ± 198 1126 ± 218 1173 ± 225                              ______________________________________                                    

                  TABLE 8                                                         ______________________________________                                        Treatment C (Comparative Example 2)                                             Free Fatty Acids in the Serum [μmol/l], MCT/vegetable oil/fish            oil (50:30/20)                                                                 Subject    after   Day 1    Day 2   Day 3                                   ______________________________________                                        1.       0 h     13         12      0                                            5 h 1051 828 863                                                             2. 0 h 271 67 82                                                               5 h 900 816 899                                                              3. 0 h 0 20 1                                                                  5 h 1010 941 1006                                                            4. 0 h 32 136 128                                                              5 h 1175 1269 1229                                                           5. 0 h 0 10 0                                                                  5 h 1139 1159 1024                                                           6. 0 h 15 34 21                                                                5 h 887 1252 1239                                                            7. 0 h 180 283 177                                                             5 h 1340 1335 1135                                                           8. 0 h 0 0 0                                                                   5 h 873 811 852                                                              Average ± st.d. 0 h  64 ± 97  70 ± 90  51 ± 65                     5 h 1047 ± 154 1051 ± 211 1031 ± 146                              ______________________________________                                    

3. Determination of Eicosapentaenoic Acid (EPA, 20:5 n-3) Incorporationin Membrane Phospholipids of Platelets (Thrombocytes) and Leucocytes

The determination of the proportion of eicosapentaenoic acid in themembrane phospholipids of the thrombocytes and leucocytes of the eightsubjects was performed by gas chromatography via the fatty acid methylesters (percent by area method).

                  TABLE 9                                                         ______________________________________                                        Treatment B (according to the invention)                                        Eicosapentaenoic in thrombocytes and leucocytes,                              MCT/vegetable oil/fish oil (50:40:10)                                                     Day 1 (0 h)                                                                             Day 2 (0 h)                                                                              Day 3 (0 h)                                ______________________________________                                        EPA in thrombocytes                                                                         0.2 ± 0.1                                                                            0.7 ± 0.1                                                                             1.2 ± 0.1                                 Average ± st.d. (% by area)                                                EPA in leucocytes 0.4 ± 0.1 0.7 ± 0.3 1.0 ± 0.3                      Average ± st.d. (% by area)                                              ______________________________________                                    

                  TABLE 10                                                        ______________________________________                                        Treatment C (Comparative Example 2)                                             Eicosapentaenoic in thrombocytes and leucocytes,                              MCT/vegetable oil/fish oil (50:30:20)                                                     Day 1 (0 h)                                                                             Day 2 (0 h)                                                                              Day 3 (0 h)                                ______________________________________                                        EPA in thrombocytes                                                                         0.4 ± 0.1                                                                            1.0 ± 0.1                                                                             1.7 ± 0.1                                 Average ± st.d. (% by area)                                                EPA in leucocytes 0.4 ± 0.1 0.9 ± 0.1 1.4 ± 0.1                      Average ± st.d. (% by area)                                              ______________________________________                                    

A comparison of the results of table 9 with those of table 10 shows thatin treatment C, for example, an EPA contents of 0.9% by area was foundin leucocytes on day 2. From the fish oil content in treatment Baccording to the invention being only half as high, an EPA content of0.45% by area would be expected. Surprisingly, however, a significantlyhigher value was found, namely 0.7% by area. A similar result isobtained for day 3 as well as for thrombocytes on days 2 and 3.

EXAMPLE 2

(in vitro)

Apoprotein Uptake into the Emulsion Particles

Of great interest is the significantly lower enrichment (t-test,two-sided) of apoprotein C-I (p<0.0001) and apoprotein C-III (p<0.0001),which are both apoproteins that inhibit both, triglyceride hydrolysisand direct uptake of the emulsion particles into the target tissue (suchas the liver), in the emulsion particles having a composition accordingto the invention (preparation example 4) will presumably result in amore thorough intravascular scavenging of lipids than with the otherlipid emulsion examined (preparation example 5).

                  TABLE 11                                                        ______________________________________                                        Uptake of Apoproteins C-I and C-III in Emulsion Particles,                      (incubation: 3 h), MCT/vegetable oil/fish oil (50.40:10) vs.                  MCT/vegetable oil/fish oil (50:30:20)                                                  MCT/vegetable oil/fish                                                                       MCT/vegetable oil/fish                                oil (50:40:10) oil (50:30:20)                                                 (Preparative Example 4) (Preparative Example 5)                             ______________________________________                                        Apo C-I Uptake                                                                            5.1 ± 0.51 23.4 ± 1.43                                        [μg] (n = 4) (n = 4)                                                       Average ± st.d.                                                            Apo C-III Uptake 30.1 ± 2.67 54.7 ± 4.00                                [μg] (n = 4) (n = 4)                                                       Average ± st.d.                                                          ______________________________________                                    

Lipid emulsions for parenteral administration will interact withendogeneous lipoproteins. During the infusion, the exogeneously suppliedemulsion partly fuses with endogeneous LDL (low density lipoprotein;d<1.006 g/ml), a lipoprotein with a high content of apoprotein B (apoB). Thus, the apo B enrichment in the fused emulsion particles isindicative of the extent of fusion of exogeneously supplied emulsionwith endogeneous LDL which has a relatively long plasma half life.Therefore, a high content of apo B in the fused emulsion particles mustbe considered indicative of prolonged residence time of the infusedlipids. Conversely, a low apo B content means a short plasma half life,corresponding to a reduced residence time in the plasma.

Two lipid emulsions according to preparative examples 4 and 5 wereincubated with human LDL in lipoprotein-poor plasma at 37° C. for 4hours, followed by a determination of the content of apoprotein B in theemulsion fraction.

                  TABLE 12                                                        ______________________________________                                        Apoprotein B Content in the Emulsion Particles,                                 MCT/vegetable oil/fish oil (50:40:10) vs.                                     MCT/vegetable oil/fish oil (50:30:20)                                                  MCT/vegetable oil/fish                                                                       MCT/vegetable oil/fish                                oil (50:40:10) oil (50:30:20)                                                 (Preparative Example 4) (Preparative Example 5)                             ______________________________________                                        Apo B Content                                                                            0.05 ± 0.05 0.27 ± 0.21                                        [mg/dl] (n = 6) (n = 7)                                                       Average ± st.d.                                                          ______________________________________                                    

The emulsion particles having a composition according to the inventionshow an apo B enrichment which is more than five times lower than thatof the other lipid emulsion examined, corresponding to a higherhydrolysis rate. The difference is significant (t-test, two-sided;p<0.05).

We claim:
 1. An isotonic lipid emulsion for parenteral administrationcomprising lipid droplets, wherein each such droplet comprisesmedium-chain triglycerides, at least one vegetable oil comprisingtriglycerides which supply omega-6-fatty acids, and at least one fishoil comprising triglycerides which supply omega-3-fatty acids whereinsaid lipid emulsion comprises, based on the total lipid content of theemulsion:from 30% to 60% by weight of the medium-chain triglycerides;from 35% to 65% by weight of the vegetable oil(s); and from 5% to 20% byweight of the fish oil(s).
 2. The lipid emulsion according to claim 1,wherein said medium-chain triglycerides comprise at least 90%triglycerides of caprylic acid (C₈) and capric acid (C₁₀).
 3. The lipidemulsion according to claim 1, wherein said vegetable oil is selectedfrom the group consisting of safflower oil and soybean oil.
 4. The lipidemulsion according to claim 1, wherein said fish oil is selected fromthe group consisting of sardine, salmon, herring, mackerel and othercold water fish oils and fish oils synthetically obtainable byre-esterification of glycerol with omega-3-fatty acids obtained byhydrolysis of cold water fish oil.
 5. The lipid emulsion according toclaim 1, wherein said fish oil contains at least 25% of eicosapentaenoicacid in said triglycerides, based on the fatty acid methyl esters of thefish oil concentrate.
 6. The lipid emulsion according to claim 1,wherein said fish oil contains at least 12% of docosahexaenoic acid insaid triglycerides, based on the fatty acid methyl esters of the fishoil concentrate.
 7. The lipid emulsion according to claim 1, wherein thetotal lipid content is from 5% to 30% by weight, based on the weight ofthe emulsion.
 8. A method for treating exaggerated inflammatoryreactions, increased risk of vascular thrombosis or severe cardiacarrythmia by parenteral administration of the emulsion of claim 1 to apatient having an exaggerated inflammatory reaction, or an increasedrisk of vascular thrombosis, or severe cardiac arrythmia.
 9. The lipidemulsion according to claim 1, wherein the average size of the saidlipid droplets is less than 1.0 μm.
 10. The lipid emulsion according toclaim 2, wherein said vegetable oil is selected from the groupconsisting of safflower oil and soybean oil.
 11. The lipid emulsionaccording to claim 2, wherein said fish oil is selected from the groupconsisting of sardine, salmon, herring, mackerel and other cold waterfish oils and fish oils synthetically obtainable by re-esterification ofglycerol with omega-3-fatty acids obtained by hydrolysis of cold waterfish oil.
 12. The lipid emulsion according to claim 3, wherein said fishoil is selected from the group consisting of sardine, salmon, herring,mackerel and other cold water fish oils and fish oils syntheticallyobtainable by re-esterification of glycerol with omega-3-fatty acidsobtained by hydrolysis of cold water fish oil.
 13. The lipid emulsionaccording to claim 2, wherein said fish oil contains at least 25% ofeicosapentaenoic acid in said triglycerides, based on the fatty acidmethyl esters of the fish oil concentrate.
 14. The lipid emulsionaccording to claim 3, wherein said fish oil contains at least 25% ofeicosapentaenoic acid in said triglycerides, based on the fatty acidmethyl esters of the fish oil concentrate.
 15. The lipid emulsionaccording to claim 4, wherein said fish oil contains at least 25% ofeicosapentaenoic acid in said triglycerides, based on the fatty acidmethyl esters of the fish oil concentrate.
 16. The lipid emulsionaccording to claim 2, wherein said fish oil contains at least 12% ofdocosahexaenoic acid in said triglycerides, based on the fatty acidmethyl esters of the fish oil concentrate.
 17. The lipid emulsionaccording to claim 3, wherein said fish oil contains at least 12% ofdocosahexaenoic acid in said triglycerides, based on the fatty acidmethyl esters of the fish oil concentrate.
 18. The lipid emulsionaccording to claim 4, wherein said fish oil contains at least 12% ofdocosahexaenoic acid in said triglycerides, based on the fatty acidmethyl esters of the fish oil concentrate.
 19. The lipid emulsionaccording to claim 5, wherein said fish oil contains at least 12% ofdocosahexaenoic acid in said triglycerides, based on the fatty acidmethyl esters of the fish oil concentrate.
 20. The lipid emulsionaccording to claim 2, wherein the total lipid content is from 5% to 30%by weight, based on the weight of the emulsion.
 21. The lipid emulsionaccording to claim 3, wherein the total lipid content is from 5% to 30%by weight, based on the weight of the emulsion.
 22. The lipid emulsionaccording to claim 4, wherein the total lipid content is from 5% to 30%by weight, based on the weight of the emulsion.
 23. The lipid emulsionaccording to claim 5, wherein the total lipid content is from 5% to 30%by weight, based on the weight of the emulsion.
 24. The lipid emulsionaccording to claim 6, wherein the total lipid content is from 5% to 30%by weight, based on the weight of the emulsion.
 25. A method fortreating exaggerated inflammatory reactions, increased risk of vascularthrombosis, or severe cardiac arrythmia by parenteral administration ofan emulsion provided in accordance with claim 2 to a patient having anexaggerated inflammatory reaction, or an increased risk of vascularthrombosis, or severe cardiac arrythmia.